JP3871375B2 - Fuel injection device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device for an internal combustion engine, and is intended to quickly correct a change in fuel injection characteristics due to a difference between cylinders and a change with time.
[0002]
[Prior art]
In a fuel injection internal combustion engine, the amount of fuel to be injected is calculated according to the engine speed and the engine load. Then, the injection time of the fuel injection valve is controlled so that the calculated amount of fuel is injected. However, the relationship between the injection amount and the injection time has a difference between the cylinders and changes depending on factors over time. For this reason, in the control based on the injection time, there is a possibility that the expected amount of fuel is not injected, or torque fluctuations occur due to variations in the fuel injection amount among the cylinders. Therefore, in Japanese Patent Laid-Open No. 62-186034, the amount of fuel actually injected from the fuel injection valve of each cylinder is grasped from the change in fuel pressure, and the actual fuel injection amount thus grasped is calculated. The calculation value of the next fuel injection amount is corrected based on the ratio of the fuel injection amount.
[0003]
[Problems to be solved by the invention]
In the prior art, the relationship between the injection amount and the injection time is common to all cylinders, and the injection amount differs from the intended value due to variations in the relationship between the injection amount and the injection time between the cylinders. In order to deal with the case, the next injection time is corrected by the ratio of the injection amount calculated in the injection of each cylinder and the injection amount calculated from the pressure drop. However, the relationship between the injection amount and the injection time is not a simple linear relationship, and the desired fuel injection amount cannot be obtained quickly in each cylinder only by the ratio between the actual measurement value and the calculated value of the injection amount.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to quickly and accurately correct a variation in characteristics of each cylinder regardless of a variation in injection characteristics so as to obtain an optimal fuel injection amount.
[0005]
[Means for Solving the Problems]
A fuel injection device for an internal combustion engine according to claim 1 is a fuel injector provided in each cylinder in a multi-cylinder internal combustion engine, a common rail connected to a fuel injection amount injector of each cylinder, and a fuel for detecting a fuel pressure in the common rail. A common rail pressure control mechanism that includes a pressure sensor and controls the value according to the operating condition of the internal combustion engine, a fuel injection amount calculating means that calculates a fuel injection quantity that conforms to each operating condition of the internal combustion engine, and a fuel injection amount calculating means In order to obtain the fuel injection amount calculated by the reference map, the fuel injector valve opening time is stored for each cylinder, and during the operation of the internal combustion engine, the fuel injector valve opening time is calculated for each cylinder from the reference map, Injector drive signal forming means for outputting to the corresponding fuel injector and the amount of fuel actually injected from the fuel injector by means of a pressure sensor. A fuel injection amount actual measurement means for each cylinder measured from a change in the common rail pressure, a fuel injection amount calculation value by the fuel injection amount calculation means, and a fuel injection amount actual measurement value by the fuel injection amount measurement means in each cylinder injection In the fuel injection device for an internal combustion engine, each of the reference cylinders is individually modified by the fuel injection amount measuring means, the change in the common rail pressure measured by the fuel injection amount measuring means is the same cylinder during steady operation. The calculated value and the actual measured value of the fuel injection amount of the means for individually correcting the respective reference maps are the difference between the minimum pressure value and the target pressure value at Each reference map is corrected by using the calculated value and the actual measurement value, and the fuel injection amount during steady operation based on each corrected map It is characterized in that for calculating the opening time of each fuel injector corresponding to the calculated value.
Further, the invention of claim 2 is preferably further characterized in that the correction value for each cylinder of the reference map is stored in a storage device capable of holding the stored contents individually even when the power is turned off.
Since the present invention is configured as described above, in particular, the reference map during steady operation in which various conditions such as changes in pump pressure, various internal combustion engine operating conditions, calculated values and actual measured values of the fuel injection amount are most stable. Since the valve opening time of each injector is calculated based on the corrected map, it is possible to obtain an effect that a precise and reliable fuel injection amount can be obtained in each cylinder.
[0006]
By detecting the fuel injection amount by the pressure drop of the pressure sensor provided on the common rail as in the invention of claim 4, the pressure drop of each cylinder is detected by using only one sensor common to the previous cylinder. It can be used for map correction of each cylinder, and the difference in fuel injection amount between cylinders and change with time can be prevented while reducing the cost.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below. In FIG. 1, 10 is a main body of a four-cylinder (multi-cylinder) diesel internal combustion engine, and 12 schematically shows a fuel injector provided in each cylinder. The fuel injector 12 is connected to a common rail 16 through a high-pressure pipe 14. Diesel fuel from a fuel tank 18 is introduced into the common rail 16 via a low pressure pump 20 and a high pressure pump 22. As is well known, the high-pressure pump 22 includes a valve mechanism (not shown) that controls the amount of high-pressure fuel introduced into the common rail 16 so that the fuel pressure in the common rail 16 becomes a predetermined value according to the engine operating conditions. In addition, the valve mechanism is controlled.
[0008]
The control circuit 24 controls the fuel injection operation by the fuel injector 12 according to signals from the sensors and internal programs and data. In this embodiment, as will be described later, the control circuit 24 is configured as a microcomputer system. The pressure sensor 26 is provided on the common rail 16, and a signal corresponding to the fuel pressure P _c of the common rail 16 is input to the control circuit 24. The crank angle sensor 28 generates a pulse signal for each predetermined rotation angle of the crankshaft, for example, 30 ° and 720 ° rotations. The engine speed N can be known from the time interval of the signal at every crank angle of 30 °. Cylinder discrimination can be performed by the 720 ° signal. The load sensor 30 generates a signal corresponding to the load L of the engine, and can be specifically configured as an accelerator pedal depression amount sensor or the like.
[0009]
FIG. 2 shows the detailed structure of the fuel injector 12. That is, the needle body 34 is attached to the tip of the housing 32 of the injector 12 by the cylindrical holder 36. A needle 38 is provided in the needle body 34, and the needle 38 opens and closes the nozzle 40 at the tip of the needle body 34. The needle spring 42 urges the needle 38 to move downward, and the nozzle 40 is normally closed by the needle 38. A high pressure passage 44 is formed in the housing 32, a lower end thereof communicates with a fuel reservoir chamber (not shown) formed in the needle body 34, and an upper end is connected to the fuel inlet 46. A high pressure pipe 14 from the common rail 16 (FIG. 1) to the injector 12 of the cylinder is connected to the fuel inlet 46. Accordingly, the high-pressure fuel from the common rail is introduced into the fuel reservoir chamber in the needle body 34 via the inlet 46 and the high-pressure passage 44.
[0010]
A command piston 48 is provided in the housing 32. The lower end of the command piston 48 is connected to the needle 38 via a connecting rod 50, and a back pressure chamber 52 is formed at the upper end. The back pressure chamber 52 is connected to the high pressure piping side (the high pressure passage 44 and the inlet 46) through the first orifice 53.
The electromagnetic valve mechanism 54 operates to control the opening and closing of the needle 38 by controlling the fuel pressure in the back pressure chamber 52. Hereinafter, the configuration of the electromagnetic valve mechanism 54 will be described. The main body 56 is screwed into the upper end of the housing 32 together with the case 58. A cylindrical valve body 60 is slidably provided in the main body 56 so that the control port 62 formed at the lower end of the main body 56 can be opened and closed. The control port 62 is always in communication with the back pressure chamber 52 via the second orifice 64. A space around the valve body 60 in the main body 56 opens to a drain port 66, and this drain port 66 is connected to a fuel system such as the fuel tank 18 (FIG. 1) via a low pressure passage formed in the housing 32. It communicates with the low pressure side part of The balance rod 68 is inserted into the center hole of the valve body 60, and a balance chamber 70 is formed at the lower end surface of the balance rod 68 in the valve body 60, and the balance chamber 70 is connected to the control port 62 or back pressure via the communication hole 72. The room 52 is always in communication. The upper end of the balance rod 68 protrudes from the main body 56 to the outside, and abuts against the core 73 made of a magnetic material. The core 73 is fixed to the center of the winding frame 74, and a solenoid 76 is disposed in the winding frame 74. An armature 78 provided integrally with the upper end portion of the valve body 60 is disposed so as to face the solenoid 76 with the end faces facing each other. The spring 80 urges the valve body 60 and the armature 78 integral with the valve body 60 in a direction away from the winding frame 74.
[0011]
In a state where the solenoid 76 is demagnetized, the valve body 60 closes the control port 62 by the urging force of the spring 80. Accordingly, the fuel pressure in the back pressure chamber 52 urges the needle 38 to move downward via the command piston 48 and the connecting rod 50, and the needle spring 42 urges the needle 38 downward. On the other hand, a force by the fuel pressure that lifts the needle 38 from the high pressure passage 44 is applied. However, since the resultant force of the fuel pressure in the back pressure chamber 52 and the spring force of the spring 42 overcomes the force of the fuel pressure that lifts the needle 38, the needle 38 is closed.
[0012]
By energizing the solenoid 76, the armature 78, that is, the valve body 60 is lifted against the spring 80, the control port 62 communicates with the drain port 66, and the pressure in the back pressure chamber 52 decreases. Therefore, the force of lifting by the fuel pressure applied to the needle 38 becomes dominant, the needle 38 is opened against the spring 42, and fuel is injected from the nozzle 40.
[0013]
When the energization of the solenoid 76 is stopped, the electromagnetic force that has been attracted to the armature 78 until then disappears, and the valve body 60 is lowered by the urging force of the spring 80 to close the control port 62. Therefore, the discharge of fuel from the back pressure chamber 52 to the drain port 66 is stopped, and the fuel pressure in the back pressure chamber 52 is increased by the high-pressure fuel flowing in through the first orifice 53, and is combined with the force of the spring 42. The force for closing the needle 38 is increased, and the needle 38 is prevailed with respect to the force by the fuel pressure that has opened the needle 38, the needle 38 is closed, and the fuel injection from the nozzle 40 is stopped.
[0014]
Next, the operation of the control circuit 24 will be described. The control circuit 24 controls the introduction of fuel from the high pressure pump 22 to the common rail 16 so that the pressure of the common rail 16 becomes a predetermined pressure corresponding to the operating conditions of the internal combustion engine. . Further, the control circuit 24 forms an operation signal to the solenoid 76 of the injector 12 of each cylinder so that a predetermined amount of fuel is injected at a predetermined timing in the injector 12 of each cylinder. When the fuel injection signal is formed, an injector valve opening time τ ₀ suitable for the operation is calculated from a map of the fuel injection injection amount installed for each injector 12 of each cylinder and the valve opening time of the injector 12, and The actual fuel injection amount is grasped from the pressure drop amount of the common rail 16 after the injection, and the map is updated based on the actually measured value and the calculated value of the fuel injection amount. Hereinafter, the operation of the control circuit 24 will be described in detail with reference to the flowcharts of FIGS. 3 to 6 and the timing chart of FIG. 7.
[0015]
FIG. 3 shows a routine for controlling the fuel pressure of the common rail 16 to a predetermined value according to engine operating conditions. This routine is located in a time interrupt routine that is executed at regular time intervals, eg, every 4 milliseconds. In step 100, the target of the common rail 16 is determined based on the engine speed N determined from the load L detected by the load sensor 30 (for example, the accelerator pedal opening) and the crank angle from the crank angle sensor 28 from the pulse signal interval of every 30 °. The pressure P _co is calculated. That is, there is a map of the target pressure P _co with respect to the load and the rotational speed in the memory, and an interpolation calculation of the target pressure P _co corresponding to the detected values of the load L and the rotational speed N is executed.
[0016]
In step 102, the detected value P _c of the common rail pressure by the pressure sensor 26 is input. In step 104, it is determined whether or not the pressure target value P _co > actually measured value P _c . If it is determined that the target value has not been reached, the process proceeds to step 106 where the high pressure pump 22 (FIG. 1) supplies fuel to the common rail 16. The amount is controlled to be increased. On the other hand, if it is determined in step 104 that P _co > P _c is not satisfied, the _routine proceeds to step 108 where it is determined whether P _co <P _c . When P _co <P _c , it is determined that the common rail pressure has reached the target value, the process proceeds to step 110, and the high pressure pump 22 (FIG. 1) is controlled so that the fuel amount to the common rail 16 is reduced. By such control, the pressure of the fuel supplied to the common rail 16 is controlled to a predetermined value P _co corresponding to the engine operating condition (see (e) in FIG. 7).
[0017]
FIG. 4 shows a fuel injection routine, which is located in a crank angle interruption routine that is executed every time a pulse signal of every 30 degrees is received from the crank angle sensor 28. In step 120, it is determined whether it is time to form a fuel injection signal in the first cylinder. In a diesel engine, fuel injection is executed in the vicinity of the compression top dead center in each cylinder. Therefore, the calculation for forming the fuel injection signal is appropriately set so that there is an appropriate margin prior to the execution of this injection. Has been. In FIG. 7, t _c represents the timing at which the fuel injection calculation is performed in the first cylinder. In a four-cylinder internal combustion engine, this timing comes every 180 degrees in crank angle. When it is determined in step 120 that the timing for forming the injection signal for the first cylinder is to be executed, the routine proceeds to step 122, and the routine proceeds to step 124 via a map correction routine for correcting the injection amount-valve opening time map. The contents of this routine will be described later. In step 124, the basic fuel injection amount Q ₀ is calculated from the load L and the rotational speed N. That is, there is a map of the basic fuel injection amount with respect to the load and the rotational speed in the memory, and in step 124, an interpolation calculation of the fuel injection amount Q ₀ corresponding to the detected values of the load L and the rotational speed N at that time is executed. .
[0018]
Next, at step 126, the fuel pressure _Pc of the common rail 16 measured by the pressure sensor 26 is read. In step 128, the injection time τ ₀ is calculated from the map of fuel injection amount Q-fuel injection time τ. That is, a map of the fuel injection amount Q and the injection time τ is provided in the memory. FIG. 8 conceptually shows the Q-τ map. That is, the fuel injection amount Q and the injection time τ have a unique relationship as long as the pressure P _{c of the} common rail 16 is constant. Further, when the pressure P _{c of the} common rail 16 is increased, the injection time of the injector 12 for obtaining the same fuel injection amount is shortened. On the other hand, the memory stores the relationship between the fuel injection amount Q and the injection time τ for each common rail pressure at a predetermined pitch. Then, the Q-τ characteristic corresponding to the calculated value of the common rail pressure is obtained by performing an interpolation operation of the Q-τ characteristic with respect to the current pressure value P _c of the common rail 16 detected in step 126. FIG. 9 illustrates how this interpolation operation is performed. In other words, the Q-τ characteristic at the map pressure with the measured value of the common rail pressure (in the example in the figure, when the measured pressure is 30 MPa, the Q-τ characteristic when the common rail pressure is 40 MPa and the common rail pressure is 20 MPa) Q-τ characteristics) are selected. Interpolation is performed every predetermined injection time (for example, every 0.2 ms), and a Q-τ characteristic corresponding to P _c = 30 is calculated as indicated by a broken line L in FIG.
[0019]
In step 130, the fuel injection time is interpolated by the Q-τ characteristic at the current measured common rail pressure _Pc obtained in step 128. That is, the fuel injection time τ ₀ corresponding to the measured value Q ₀ of the basic fuel injection amount is interpolated as shown in FIG.
In step 132, the fuel injection timing t ₀ is calculated from the load L and the rotational speed N. That is, the memory has a map of the fuel injection timing t _{0 with} respect to the load and the rotational speed. In step 124, an interpolation operation of the fuel injection timing t ₀ corresponding to the detected values of the load L and the rotational speed N at that time is executed. The In FIG. 7, (D) schematically shows changes in the injection rate in the injection from the injector 12. The fuel injection timing t ₀ calculated in step 126 is the time when the fuel injection from the nozzle 40 is actually started after the fuel injection signal to the injector 12 is output ((b) in FIG. 7).
[0020]
In step 134, the start time (injection signal on time) t _i of the fuel injection signal to the solenoid 76 (FIG. 2) of the injector 12 and the stop time (injection signal off time) t _e of the injection signal are calculated. . That is, on-time t _i of the injector in consideration of the operation delay time of each part of the injector 12 ([delta] _t) so that the actual injection is t ₀ is the start of the (d) of FIG. 7 is calculated, whereas, the injector The off time t _{i of} 12 corresponds to the time after elapse of the fuel injection time τ ₀ calculated in step 130 from the time t _i .
[0021]
In step 136, t _i and t _e calculated in step 134 are set in a comparison register (not shown) in the control circuit 24. Therefore, as is well known, an ON signal is applied to the solenoid 76 of the injector 12 of the first cylinder at which the time t _i arrives, and fuel injection is started when the time t ₀ comes after a predetermined delay. Further, when the time t _e comes drive signal of the injector is turned off.
[0022]
Step 138 indicates the setting of the detection period t _{A to} t _B of the pressure drop of the common rail 16 accompanying the fuel injection from the injector 12 of the first cylinder. That is, (e) in FIG. 7 shows the pressure drop of the common rail 16 due to the start of injection by the injector 12. Prior to fuel injection, the pressure on the common rail is controlled to the predetermined pressure P _co determined by the operating conditions of the internal combustion engine. Due to the opening of the injector 12 at t ₀ , the pressure in the common rail 16 begins to drop. P _MIN indicates the minimum value of the common rail pressure. When the injection from the injector 12 stops, the pressure of the common rail 16 increases, and the pressure of the common rail is returned to the predetermined value P _co by the control described with reference to FIG. Therefore, the pressure drop ΔP due to the execution of one fuel injection from the injector 12 is expressed as P _co −P _MIN , and the actual fuel injection amount can be grasped from this pressure drop. The pressure drop detection interval t _{A to} t _B is set with an appropriate margin before and after the time when the pressure of the common rail after the fuel injection is expected to drop. In step 140, t _A and t _B calculated in step 138 are set in a comparison register (not shown) of the control circuit. When time t _A arrives, a flag (F) indicating the pressure drop detection period of the first cylinder is set as shown in FIG. 7C, and when time t _B arrives, this flag is reset.
[0023]
In step 142, it is determined whether or not it is the injection calculation timing of the second cylinder, whether or not it is in the injection calculation timing of the third cylinder in step 144, and whether or not it is in the injection calculation timing of the fourth cylinder in step 146. The The processing when it is determined that the injection calculation timing of the second to fourth cylinders is the same as the processing of steps 122 to 140 for the first cylinder, the correction of the Q-τ map for each cylinder (step 122), The calculation of the basic injection amount Q ₀ and the injection timing t ₀ of the cylinder (steps 124 to 132) and the setting of the injection signal (steps 134 to 136) are performed, and the common rail pressure detection period by injection is set for each cylinder. (Steps 138-140).
[0024]
FIG. 5 shows a pressure drop detection routine, which is located in a time interruption routine executed at regular intervals. In step 150, it is determined whether or not it is during the pressure drop detection period due to the injection of the first cylinder. As shown in FIG. 7C, the flag F is set in the period t _{A to} t _B after the injection of the first cylinder. When F = 1, the routine proceeds from step 150 to step 152, where the pressure by the pressure sensor 26 is increased. The measured value P _c is entered into P _i as the current common rail pressure. In step 154, it is determined whether or not the minimum value P _MIN > P _{i of the} common rail pressure. If it is determined that P _MIN > P _i , the process proceeds to step 156 and P _MIN is updated with P _i . By performing such processing, the minimum value P _MIN of the common rail pressure due to the injection of the first cylinder can be detected.
[0025]
In step 160, it is in the pressure drop detection period of the second cylinder, in step 162, in the pressure drop detection period of the third cylinder, in step 164, in the pressure drop detection period of the fourth cylinder. Are judged respectively. The processing when it is determined that the pressure drop detection period of the second to fourth cylinders is the same as the processing of steps 152 to 156 for the first cylinder, the minimum value P _MIN of the common rail pressure due to fuel injection of each cylinder Detection is performed.
[0026]
FIG. 6 shows the details of the map correction routine performed in step 122 of FIG. In step 168, it is determined whether the engine is in a steady state. This determination can be made based on a predetermined change in the rotational speed or load of the internal combustion engine. If the operation is steady, the routine proceeds to step 170. In step 170, subtracting P _MIN from the common rail set pressure P _co reduces the common rail pressure drop (ΔP) in the injection of the first cylinder at the previous time (720 degrees before the crank angle). Is calculated, and the actual injection amount Q ₁ in the previous injection is calculated from this pressure drop. This is basically the same as the method disclosed in Japanese Patent Application Laid-Open No. Sho 62-186034, and can be calculated from a fuel temperature in the common rail and a common rail volume by a predetermined calculation formula. In step 172, the correction term Δt of the fuel injection time τ is calculated from the injection amount calculation value Q ₀ and the actual measurement value Q _{1 using a} map. That is, the map value of the injection time at the calculation value Q ₀ is τ ₀ , but since the actual measurement value is Q ₁ , the correction term Δt is Δt = ((Q ₁ −Q ₀ ) / Q ₀ ) × τ ₀
It can be. In the present invention, since the map of the injection amount Q-injection time τ is provided for each cylinder, the map of each cylinder is adapted in the initial state, and therefore no correction is necessary. Therefore, the desired fuel injection amount can be obtained immediately regardless of changes in operating conditions. However, since the injection characteristics change due to changes over time (such as clogging of the nozzle holes), correction is required.
[0027]
In step 174, it is determined whether or not the correction term Δt is larger than a predetermined upper limit value x (guard value), and in step 176, it is determined whether or not the correction term Δt is smaller than a predetermined addition value −y (guard value). If so, the process proceeds to step 178 and the map value is corrected. As shown in FIG. 10, the map value is corrected by correcting the fuel injection time τ by Δt for the map points A, B, C, D on the map surrounding the points Q ₀ , τ ₀ . That is, in FIG. 11, the corrected map points are represented by A ′, B ′, C ′, and D ′.
[0028]
The Q-τ map of each cylinder corrected in FIG. 6 is stored in a flash memory or the like that can retain the contents even after the ignition key switch is turned off. Therefore, even when the internal combustion engine is restarted, the optimum fuel injection control can be executed for each cylinder immediately.
In FIG. 6, when the correction amount is excessive or small, an alarm indicating that the abnormality (for example, clogging of the injector nozzle) has occurred can be issued to the driver. Further, the routine of FIG. 6 may be performed every time the vehicle travels for a certain period of time.
[Brief description of the drawings]
FIG. 1 is an overall schematic view of a diesel engine equipped with a fuel injection device according to the present invention.
FIG. 2 is a detailed cross-sectional view of the injector of FIG.
FIG. 3 is a flowchart of a common rail pressure control routine.
FIG. 4 is a flowchart of a fuel injection routine.
FIG. 5 is a flowchart of a common rail pressure drop detection routine.
FIG. 6 is a flowchart of a fuel injection amount-injection time map correction routine.
FIG. 7 is a timing chart showing the operation of the fuel injection device.
FIG. 8 is a diagram schematically showing a fuel injection amount-fuel injection time map;
FIG. 9 is a diagram for explaining an interpolation method of a fuel injection amount-fuel injection time map;
FIG. 10 is a diagram for explaining a method for correcting a fuel injection amount-fuel injection time map;
FIG. 11 is a diagram for explaining in more detail a method for correcting a fuel injection amount-fuel injection time map;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Diesel internal combustion engine main body 12 ... Fuel injector 14 ... High-pressure piping 14
DESCRIPTION OF SYMBOLS 16 ... Common rail 22 ... High pressure pump 24 ... Control circuit 26 ... Pressure sensor 28 ... Crank angle sensor 30 ... Load sensor 34 ... Needle body 38 ... Needle 40 ... Injection hole 52 ... Back pressure chamber 54 ... Solenoid valve mechanism 60 ... Cylindrical valve body 62 ... Control port 66 ... Drain port 76 ... Solenoid 78 ... Armature

Claims (2)

A fuel injector provided in each cylinder in a multi-cylinder internal combustion engine;
A common rail connected to the fuel injector of each cylinder;
A common rail pressure control mechanism that includes a fuel pressure sensor that detects the fuel pressure in the common rail, and controls the fuel pressure to a value according to the operating conditions of the internal combustion engine;
A fuel injection amount calculating means for calculating a fuel injection amount suitable for each operating condition of the internal combustion engine;
A reference map in which the valve opening time of the fuel injector is stored for each cylinder in order to obtain the fuel injection amount calculated by the fuel injection amount calculating means;
Injector drive signal forming means for calculating the valve opening time of the fuel injector for each cylinder during operation of the internal combustion engine from the reference map and outputting to the corresponding fuel injector;
Fuel injection amount measuring means for actually measuring the amount of fuel actually injected from the fuel injector for each cylinder from a change in common rail pressure by a pressure sensor;
In each cylinder injection, there is provided means for individually correcting each reference map based on the calculated value of the fuel injection amount by the fuel injection amount calculating means and the actually measured value of the fuel injection amount by the fuel injection amount actualizing means. In a fuel injection device for an internal combustion engine,
The change in the common rail pressure measured by the fuel injection amount measuring means is a difference between the minimum pressure value and the target pressure value in each of the same cylinders during steady operation, and each of the reference maps is individually corrected. The calculated value and the actually measured value of the fuel injection amount are set to the calculated value and the actually measured value of the fuel injection amount in the same cylinder at the time of steady operation, thereby correcting each reference map and based on each corrected map. A fuel injection device for an internal combustion engine that calculates a valve opening time of each fuel injector corresponding to a calculated value of a fuel injection amount during steady operation.   2. The fuel injection device for an internal combustion engine according to claim 1, wherein the correction value for each cylinder in the reference map is stored in a storage device that can retain the stored contents even when the power is turned off individually.

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